The present invention relates to fluid valves and more particularly to a multi-port valve assembly.
At the present time it is known that the flow of fluids, such as gases and liquids, may be controlled by various types of valves. In certain situations, it may be necessary to have a number of valves in one location, with each valve controlling a different fluid path. It may also be desirable that the valve control be automatic, as distinct from an individual manual control; or that the valves operate in a certain timed sequence or be controlled from a remote location.
One solution for such an assembly of valves, called a "multi-port valve apparatus", is to gather a number of individual valves as part of one physical assembly, for example, by securing them closely together on a common manifold. Each of the valves is individually controlled, by its own electrical switch, and the valves are solenoid operated. The closure of the switch will either open or close the valve, depending upon the spring and solenoid arrangement. Such a multi-port valve apparatus, using a solenoid valve, if constructed of high quality valves which are tight against even the smallest leakage, i.e., "bubble-tight", are quite expensive. Further, since each valve has its own solenoid, its own electrical line and its own switch, as the number of valves increases, so does the chance of the system developing a mechanical or electrical fault. If the system is subject to an adverse environment, such as corrosive gases or physical shocks, the chances of failure, either of their mechanical portions or of their electrical portions, such as the solenoids, is increased.
One particular function, for which the multi-port valve apparatus of the present invention is particularly adapted, is to sample atmospheric gases at different elevations. The gas samples are collected in container bottles and each bottle has two valves, an inlet valve and an outlet valve. The entire system is placed aboard an airplane and the airplane is flown at different heights. At each selected height, both valves of the bottle are opened, the container bottle is purged and then one valve is closed and that bottle is filled with the ambient air pumped from that height. The second valve of that bottle is closed, so that the gas sample collected at that height is retained within the bottle, and the containers are brought to a laboratory for analysis. It is essential, for accurate analysis, that the samples be extremely clean so that all the materials of the collection system must be free of outgasing. For example, if nine bottles are used, then the system requires eighteen valves, each of which must be air-tight and completely clean.
The use of a solenoid type multi-port valve apparatus, in the function of collecting ambient air at various altitudes, and in other functions, has the following various disadvantages. If the valves are normally closed, i.e., spring-loaded to close, it requires continual power to keep them open, which is a drain on the power source. The size of the valve ports is limited, which limits the flow rate, and it is difficult and expensive to obtain ports larger than 1/8-inch in diameter. Each solenoid valve has a number of moving parts and a number of electrical connections, which limits their reliability. The solenoid operates against a spring and the spring closes the sealing mechanism. Consequently, to obtain a greater sealing force requires a heavier spring and a stronger solenoid, which seriously limits the sealing force. In one type of solenoid valve, the valve seat has a globe shape, which is difficult to seal against small stray particles. It must be heated to operate in cold environments, such as at high altitudes.
The patent literature shows a series of patents which are directed to multi-port valve assemblies and to single valves which use a belt. In U.S. Pat. No. 4,241,761 entitled "Manifold Valve Assembly", a row of ports are selectively controlled by individual valve stems. Each of the valve stems consists of a flexible nipple which encloses a rod, which is spring-loaded and terminates in an actuating button. U.S. Pat. No. 3,752,223 entitled "Air Conditioning Apparatus For Automotive Vehicles" shows a manifold which is manually slidable in a track. The manifold is hollow and has orifices which connect with ducts, the connection between the orifices and the ducts depending upon its position. U.S. Pat. No. 3,223,019 entitled "Linear Air Diffuser" shows an air distribution system in which a damper plate is slidably engaged on a diffusion wall and controls the air flow through openings. U.S. Pat. No. 4,037,108 entitled "Ion Source With Capability of Changing Between Operation Load" is not a fluid valve but rather is an electronic ionization source. The type of ion source, whether an electronic impact ionization or a chemical ionization, is determined by movement of a belt over ports of a cavity. U.S. Pat. No. 3,726,313 entitled "Reciprocating Valve" shows the principles of a roller-band device applied to a single valve.